Remediation-focused predictive tools for polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) rely on transformation models to evaluate the reduction in total contaminant load and toxic equivalency (TEQ). In this study, a comprehensive model predicting the profiles of PCDD/F congeners and the associated TEQs was developed. The model employs first-order kinetics to describe the transformation of 256 reactions for 75 PCDD congeners and 421 reactions for 135 PCDF congeners. It integrates the growth of anaerobic microbial guilds using Monod kinetics on hydrogen release compounds and stoichiometric growth for Dehalococcoides sp. The effects of temperature, salinity, pH, and availability of vitamin B12 (a cofactor) were also integrated. The PCDD/F congeners model was used to extract the first-order dechlorination rate constants from a number of pure culture and mixed microbial microcosm studies. Simulations for the transformation of PCDD/F congeners at concentrations representative of the Tittabawassee or Saginaw Rivers and watershed in MI, USA were carried out. For a starting TEQ of 5000 ng per kg dry sediment (ppt), the model predicted a decrease in the overall TEQ to below 2000 ppt after 2.6 years and below 250 ppt after ∼21 years. The developed model may be used for extracting rates from microcosm studies and to evaluate the effect of engineering interventions on TEQ reduction.

中文翻译：

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预测多氯二苯并对二恶英和二苯并呋喃（PCDD/F 同系物）脱氯引起的毒性当量 （TEQ） 降低的综合模型


多氯二苯并对二恶英 （PCDD） 和多氯二苯并呋喃 （PCDF） 的以修复为重点的预测工具依靠转化模型来评估总污染物负荷和毒性当量 （TEQ） 的减少。在这项研究中，开发了一个预测 PCDD/F 同系物谱和相关 TEQ 的综合模型。该模型采用一阶动力学来描述 75 个 PCDD 同系物的 256 个反应和 135 个 PCDF 同系物的 421 个反应的转化。它使用氢释放化合物的 Monod 动力学和 Dehalococcoides sp 的化学计量生长整合了厌氧微生物公会的生长。还整合了温度、盐度、pH 值和维生素 B12 （一种辅助因子） 可用性的影响。PCDD/F 同系物模型用于从许多纯培养物和混合微生物微观研究中提取一阶脱氯速率常数。对美国密歇根州 Tittabawassee 河或 Saginaw 河和流域的浓度下 PCDD/F 同系物的转化进行了模拟。对于每公斤干沉积物 （ppt） 5000 ng 的起始 TEQ，该模型预测整体 TEQ 在 2.6 年后下降到 2000 ppt 以下，在 ∼21 年后下降到 250 ppt 以下。开发的模型可用于从微观研究中提取比率，并评估工程干预对 TEQ 降低的影响。